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This New Map Shows Your Risk of Catching Lyme Disease

If you don’t live in the northeastern United States, you may not think much about diseases transmitted by ticks. If you do live there, or spend part of the summer along the coastal arc that stretches from Virginia and Maryland up through southern Maine, consciousness of these sneaky, potentially disabling illnesses—Lyme disease and its lesser-known brethren, including erlichiosis, anaplasmosis, babesiosis and the rest—is hard to escape.

That very regionalized awareness occurs both because Lyme can be a dreadful illness, causing arthritis and neurological problems years after the tick bite that transmitted it, and also because Lyme is oddly geographically limited. It is named for the town where cases in kids were first identified and linked, Lyme, Conn., and still is most likely to occur in New England and nearby states.

If you are a resident or visitor to that area, though, it has been hard to understand just how much at risk you are. To date, the Lyme disease maps published by the Centers for Disease Control and Prevention have pinpointed Lyme disease clusters with literal pinpoints—one point per reported case, as in the map below from 2013.

Reported Lyme diseases cases by state, 2013, CDC. Original available here.
Reported Lyme disease cases by state, 2013, CDC. Original available here.

Now, though, the CDC has re-analyzed its Lyme data to produce a new map, which displays the areas of highest risk of catching the disease by county. Compiling the map, which appears in a paper published online last week in the CDC’s journal Emerging Infectious Diseases, made two things clear. First, where the highest risks are, and second, that the areas of highest risk are expanding.

from Kugeler et al., Emerging Infectious Diseases, August 2015. Original available here
from Kugeler et al., Emerging Infectious Diseases, August 2015. Original available here.

The map displays counties where cases of Lyme disease are at least twice as high as epidemiologists would predict based on the size of the county’s population. To make that determination, it uses data collected in four 5-year periods: 1993-97, 1998-2002, 2003-07, and 2008-12. Over that 20-year period, only a few counties fell off the high-risk list. Many more were added.

Here’s what the map and the data behind it show:

In 1993, 69 counties in the US had enough cases to qualify as high-risk areas. In 2012, the number was 260, almost 4 times as many.

In 1993, the high-risk counties were concentrated in Connecticut, New York and New Jersey, and a few counties in western Wisconsin. The most recent data shows high-risk areas in 17 states. Lyme is expanding “in all accessible directions,” the paper says.

In the Midwest, the most high-risk areas have remained the same over 20 years. On the East Coast, though, they have moved, away from the coast and into eastern Pennsylvania.

A little more on which counties, exactly. Many people can probably look at those maps and get a good sense of where their houses or relatives are. I’ve asked the CDC whether there’s a version of the map that includes county names. In the meantime, an Excel spreadsheet that the CDC separately makes available on its website lists counties and reported cases since 1992. When I sort it by by most recent data, the top counties come up, in order, as: Chester County, Penn.; Bucks County, Penn.; Middlesex County, Mass.; New Castle County, Del.; and Morris County, NJ.

Why is Lyme expanding? The CDC paper, written by Kiersten J. Kugeler, PhD  and colleagues, doesn’t speculate. Other research, though—especially at the Cary Institute of Ecosystem Studies in upstate New York—has documented that Lyme is more likely to occur where suburban development breaks up existing forest. Their work has found that, the smaller the chunks an ecosystem is carved into, the greater the chance that the most important animal in the Lyme-disease transmission cycle, the white-footed mouse, can flourish without pressure from predators.

What that means is this: One way to gauge your risk from Lyme is to study this new map and pinpoint your location. But another way, if you live in the risky areas, is to look around you for mega-mansions and new subdivisions forcing clearing of formerly undeveloped land. When you see that—and with the resurgence of the economy, you will—take an extra look for ticks after you go outside.

30 thoughts on “This New Map Shows Your Risk of Catching Lyme Disease

  1. Also, the folks building the new McMansions and developments should be encouraged to use native plants. The ubiquitous red Japanese barberry, for example, which is often planted as a low maintenance ornamental, encourages the tick population. As U. Conn researchers noted, “we find 120 infected ticks where Barberry is not contained, 40 ticks per acre where Barberry is contained, and only 10 infected ticks where there is no Barberry.” The barberry, now considered an invasive, serves as a “tick nursery,” given how it alters the local microenvironment.
    Please encourage garden centers and landscapers to use native plants and remove barberry.

  2. A caution with interpreting these maps is that the reported cases are based on the county of residence at the time of diagnosis, not the county of exposure. While that is often the same place for most cases, for others the counties could be hundreds of miles apart. The authors of the new study adjust for this somewhat by using 5-year pooled incidence data. You can see that in the midwest where clusters in population centers like Chicago, Milwaukee and Minneapolis in the 2013 data largely disappear in the 2015 map, where risk is concentrated in NW Wisconsin. Many people from those large cities engage in recreational activities in areas of higher risk — it’s not just about where you live, but where you spend your time outdoors.

    MM: Thanks Craig for the caution. IIRC a few years ago there was an anomalous case of tickborne disease on the West Coast — turned out the victim had gone hiking in New England while on vacation.

    1. Thank you for making an important point. In May 2009 I stepped outside for approximately five minutes to separate and wild horse and a bunch of kids went right back inside. We were visiting family in Mountain Grove, Missouri. This was Wednesday, May 27 and Friday, May 29 I found a tick in my ankle that I sent to a laboratory called Clongen, and it tested positive for Lyme disease. The blog has the entire story with photographs of the tick, there is the DNA test result posted on that blog. I also created the video that comes up in a search for “7 lyme facts”. ***LYME DISEASE is so much bigger than authorities are putting on.

  3. Interesting comment re Barberry.

    Another study suggests that since Chipmunks are vectors for Lyme et al., you could make “tick tubes” (cotton, wool etc treated with Permethrin and inserted into a toilet-paper tube), Chipmunks will use it as nesting material, reducing the number of ticks around your home by about 50%.

    I make it convenient for them by shoving 3″ of the tubing into their homes.

  4. I have Lyme and it is a life change! I live in Colorado and have not been east in decades so l think the Lyme is in the west now! My symptoms are pain in the feet swelling in the legs super tired. I saw seven doctors with these systems and ALL of them said people get edema! Well my wife found the Lyme on the net and I got tested positive for Lyme. The doc gave my antibiotic treatment 200mg of Doxy for 28 days and Lyrica for the foot pain. This battle has been going on for 4 years. I had to retire at age 52 and now I am a full time fighter of Lyme. I left out lots of Pain! !!!!!!!!!

  5. Total numbers per county (or state for that matter) create large errors in terms of the most infected areas. The data needs to be run through the incidence per 100,000 to get meaningful comparisons.

  6. I have concern with regard to non-reporting physicians. I live in Louisville, KY. There are few physicians who will acknowledge that Lyme & co-infections exist here and almost none that will test or report. Our state shows virtually no cases of Lyme disease, yet my PCP told my son in 2013 that in had three people test positive that summer from one just one very tiny area just outside of our city. It is much the idealistic approach that toddlers take when they put their hands over their eyes: If I don’t see you, you aren’t there. If they don’t acknowledge it, it doesn’t exist.

    Southern Indiana is much the same way. A child who had tested positive twice by CDC standards was left unreported and untreated for years because his physician told his mother that “Lyme Disease doesn’t exist in Indiana.” He had Lyme and Bartonella.

    For Louisville to have a Medical School, (at least) two teaching hospitals, and a glut of hospitals in general, we are years behind the rest of the country with regard to up-to-date knowledge, testing and treatment — of many illnesses.

    1. I agree 110% Lynne, it is ludicrous for states not to test and report for the simple fact that they do not want the truth to be told. This is an epidemic and the worst part is no one is standing up and taking steps to stop it, to treat it correctly or even recognize it for that matter. I know of several people in Kentucky that have died from Lyme and have family members who are infected with Lyme or other Tick borne illnesses, and for the CDC and the State to not recognize it and quietly sweep it all under the rug as if there aren’t any cases here and none of this is happening is negligent in my eyes. If no one will stand up for the individuals who are sick and if those who have control of the treatment of this disease or even capabilities of researching how to treat this epidemic, wont even acknowledge it’s existence or severity, then how are we ever going to being to truly help those that are sick??!!! There are more cases of Lyme disease than there were of HIV and AIDS however NO ONE WANTS TO ADMIT IT. It is high time that the Doctors and the CDC pull together and come up with a plan for the long term treatment of Lyme and the other diseases that usually accompany it. This disease isn’t going away, it’s time to start letting everyone know how many cases Kentucky really has!!

  7. They forgot to add Texas to the map! I think every state is affected now. There are no borders for ticks. I was bitten on 3 different occasions in Texas and am battling Lyme and its multiple and clever bacteria.

  8. I live in Texas. I was bit by a infected tick living in Terrell, Texas in 1994. I spent 9 years fighting with doctors over having Lyme Disease. I have now had positive Lyme going on 21 years. So just because you don’t live on the East Coast or in the Midwest doesn’t mean you have nothing to worry about being bit by a tick! Get tested no matter where you live or vacation!

  9. Tests are not accurate and docs don’t check for co-infections so they are missing lots of cases. I was finally diagnosed and treated after one year of being sick but still had pain in my feet esp in the morning. Turns out I also had Bartonella and needed a different antibiotic to treat it.

  10. Lyme has been found in every U.S. state except for Hawaii, in Canada, and in every continent except Antarctica. It is under-reported in areas that do not yet recognize Lyme; in these states, people are often misdiagnosed. This is why we started the Lyme Disease Challenge- to bring much more awareness to the fastest growing infectious Disease around. Recent studies have shown that Lyme bacteria can survive the Arctic. It can be transmitted congenitally and through the blood supply. Tests fail to check for every strain and people often have false negatives. See http://www.LymeDiseaseChallenge for more info.

  11. Do you want to put National Geographic back on the map? Look deeply into all tick borne infections. Check out #Bartonella #Babesios and most of all, check out #lymediseasechallenge. There are so many people suffering from chronic tick borne disease it is beyond comprehension. Our CDC, IOM, IDSA, and NIH are all owned by Big Pharma who do not want the truth to be known that all of the lifetime consumers of band aid drugs could actually be cured of bacterial and parasitic infections if they would only allow reliable testing to be the rule.

    MM: Thanks very much Karen and everyone for the comments about Lyme co-infections. It’s a situation I am well aware of — I did an investigation into co-infections for SELF Magazine a few years ago — and it is probably time to revisit the subject. You can find that story here and some of my other stories about Lyme here.

  12. Prevention is paramount. When going out to hike or walk in wooded areas, ALWAYS cover your feet, legs, arms and neck area. Spray with tick / insect repellent, and upon returning home, remove outside clothes and inspect the clothes and your body. It may be annoying to do this, but it may prevent you from a lifetime of suffering the consequences of Lyme and other tick borne diseases. I have recently read there is another, even more dangerous disease being transmitted by ticks on the east coast. Stay safe!

  13. the CDC’s map is misleading. yes, the northeast has traditionally been the highest rate of infection. However, tick-borne illnesses, specifically Lyme disease is spreading across the country at an alarming rate. In California, Texas and Florida, tick season is year round. The California Bay Area is reaching epidemic numbers. Also, the dots on the CDC map shows “reported” cases, we believe that the numbers are actually 10 times higher than reported. It is extremely important to provide information across the country that this is NOT just a northeastern problem – we worry that readers will have a false sense of security by viewing the CDC’s map. please visit our site, or contact me for more information. http://www.bayarealyme.org. Our mission is to make Lyme disease easy to diagnose and simple to cure. Bay Area Lyme Foundation is the largest funder of Lyme research and prevention projects across the US. It is much easier to take steps to prevent the disease, than it is to diagnose and cure this insidious disease.

  14. There is plenty of Lyme disease (and co-infections) in the western US. Most doctors are misinformed believing it to be rare because of the low numbers of reported cases. There are various reasons for this. One is that the inaccurate ELISA test required for CDC surveillance criteria is based on a single East Coast strain. There are over 15 West Coast strains so the results are likely to be negative. In Oregon, doctors are reported to the medical board for over diagnosing and over treating Lyme disease. So the intelligent doctors who help people never report their cases. Please see… http://lyme.kaiserpapers.org/lyme-disease-information-for-western-states.html and http://lyme.kaiserpapers.org/20-reasons-why-lyme-disease-is-undiagnosed.html

  15. Your map is misleading. I live in Louisville Kentucky and contracted Lyme and co-infections five years ago. Unfortunately, due to the CDC requirements I was not considered positive. I was one band short. As a result, I was not treated or reported.

    MM: The map is from the CDC; its not mine or NatGeo’s. Thanks for sharing your experience.

  16. Lyme has been in Canada for many decades also. I was infected in the 80s. People are kidding themselves if they think it’s not I your backyard……

  17. The CDC and doctors in the West seem to think there is no way someone can contract Lyme in my area but I was bitten at age 10 in California and again at age 20 in Nevada. I was misdiagnosed with Arthritis, Chronic Fatigue Syndrome, Peripheral Neuropathy, PTSD, Fibromyalgia and Somatic Pain Disorder. I was given so many drugs to treat all these symptoms that I was unable to walk, talk, work or feed myself. Once I was diagnosed 2 years ago I spent my entire life’s savings, cashed in my retirement and borrowed all the money I could to treat it because my insurance company would not acknowledge it was possible for me to have Lyme. Now that I am cured, they still won’t treat my nerves that were severely damaged by the disease. http://www.gofundme.com/xxfyz45w

  18. There is no Lyme disease in Arkansas according to the Arkansas Health Department. When I was diagnosed with Rocky Mountain Spotted Fever and Lyme disease the Health Department called me about RMSF. I asked them if they had questions about my LD diagnosis and they told me “No, that is not a reportable disease.” There will be no LD in AR until the Health Dept pulls its head out of the sand.

  19. Lyme Disease is under reported and misinterpreted in Texas and the South I believe. Because it has not been seen by many M.D.s and veterinarians, it is out of sight, out of mind, but that does not mean it is not here.

    And as far as the statement about Canada, I am sure you have ticks. I’ve read about them killing numbers of the moose population in the Northern U.S. A border won’t stop them or any of the tick diseases; it is just a matter of time, but it is probably already there.

  20. This map is misleading… there is Lyme in California. I was bitten in the Bay Area in 2008, and currently under long-term treatment at a local tick-borne disease clinic. I have Lyme, Bartonella, Babesia duncani and Mycoplasma, when I was bitten and had the typical bulls eye rash but no one recognized it as such – I was given a piddly 10 days of antibiotics and told I would be fine. Because of all the CDC- driven misinformation in the health community my initial infection turned into chronic Lyme. I’m lucky I can still hold down a job but it’s been a terrible battle.

  21. I’m a former resident of southeastern WI. When I was bitten, I had the bullseye. At the time I thought it was odd that a tick bite had become what looked to be infected. As a child who grew up in the South and played in the woods often, I picked off ticks constantly. After 15 years of seeking treatment for morosely debilitating body pains and fatigue, one doctor in D.C. finally gave me a Chronic Lyme diagnosis. When I went to the doc in WI, she drew blood to send to a lab, but didn’t say why (I had not heard of Lyme Disease at that time), put me on ten days of abx, and wrote to say the test was negative. So much for an educated public. Thank you for putting a spotlight on this much needed conversation, education and awareness building topic!

  22. Ticks infected with borrelia and babesia have been found by a Stanford University research team under picnic benches in urban parks in the SF Bay Area. They wait for people wearing shorts to sit down and then hop aboard.

  23. I am glad for the reports and the maps. It is very hard to have any accurate maps due to the lack of information or sluggish speed in which the data is being produced. Any promotion of information that is factual or close to the truth is better than none.
    I can only hope that someday all the information can be reflected so that people will understand this is a pandemic situation. The public deserves truth and the insurance companies can save millions if not billions by treating the disease instead of the “yellow brick road” of other diagnosis that the IDSA and the investors in immunizations have guided our medical community to take.
    Thanks for the information.

  24. a deadly infection is now becoming a problem with ticks- powassan (sp?)- causes swelling of the brain- and has killed folks

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